The invention relates to a discharge lamp having a light source, a glass stem, a pair of leads embedded in the glass stem, a glass envelope surrounding the light source, and a wire frame member with a first end fixed with respect to the stem, an axial portion extending parallel to the axis of the lamp, and a second end resiliently fitted in a closed end of the glass envelope.
Existing high intensity discharge lamps typically utilize a metal frame member which supports an arc tube concentrically in the glass envelope and provides current for one of the electrodes of the arc tube. A first end is connected to a lead and the remote second end has means such as welded-on leaf springs for positioning and stabilizing the frame and arc tube assembly in the envelope. As the assembly is inserted into the glass envelope, the springs collapse to conform to the inside diameter of the closed end of the envelope. The resilience of the springs centralizes the assembly and maintains its position.
The frame of the prior art is a complex manufacture due to the need to weld the metal leaf springs on the second end. Due to variations in the dimensions of the glass envelope and the leaf springs, the insertion of the assembly into the envelope can be difficult and may damage the springs or the glass. This problem is exacerbated by the emerging use of lead-free glass for lamp envelopes. Lead-free glass has less lubricity than leaded glass and offers more resistance to insertion.